Studies And Applications Of The Separation And Preconcentration Of Trace Precious Metals On The PE Double Membranes Resin And Determination With AAS

Precious metals include Ru, Rh, Pd, Os, Ir, Pt six elements of platinum clan and Au, Ag elements. The content is very low and even trace in nature. But these precious metals and its compounds have some extra physics, chemistry and biology effect. It is widely used in industry and also increases value in research. People has done many studies, but the extra trace analysis is still recognized a difficult problem in analytical chemistry. How to produce high analysis speed and good selectivity analysis method is the direction of study to the scientists and scientific researchers around the world. On the basis of numerous references, author has synthesized a double membranes resin, namely PE-dithizone. Using double membranes resin that was packed into chromatographic column as stationary phase, the separation and concentration behavior of gold, sliver and palladium in the extraction chromatography has been studied respectively. And also new methods have been established for analysis and determination of trace gold, sliver and palladium. At the same time, PE-dithizone has been packed into the micro-columns that it was used in the system of FI-FAAS, in which on-line concentration and separation and determination of palladium has been studied. The results showed that have high analysis speed and good selectivity to palladium was obtained in this automatic FI-FAAS system. This paper consists of four chapters: In chapter one, the synthetic procedure of PE-dithizone double membranes resin was described. The resin was packed into conventional column then was used to separate and concentrate trace palladium and humble metals. Palladium was eluted using 1.67mol/L glycol-0.5mol/L sodium hydroxide as eluent, and then determined by flame atomic absorption spectrometry. The recovery percent was 94.5~101%, with good results. In chapter two, a flow injection on-line separation and concentration flame atomic absorption spectrometric method for determination of trace palladium in waste catalyst was studied. In this flow network, palladium in HCl medium (pH=2) was pump through micro-column that was packed in PE-dithizone double membranes resin. Sample was pumped through it at the rate of 7.0 mL/min. In the 90s sample time, palladium was absorbed and then eluted into the nebulizer of FAAS by 1.67mol/L glycol-0.5mol/L sodium hydroxide. At the sampling frequency of 30/h, an enrichment factor of 42, a concentration efficiency of 21.0/min and a consumptive index of 0.24mL were obtained. The linear calibration range was 0~1500μg/L. The relative standard deviation was less than 2.7%. The method has been applied to the catalyst sample analysis. The recovery percent of palladium was 93.2~103%. In chapter three, the synthetic procedure of PE-dithizone double membranes resin and the optimum conditions for separation and concentrations of sliver was studied. Sliver can be concentrated on the resin in 1 mol/L HCl. The eluted by 0.5mol/L sulforea-0.3 mol/L NH4Cl and determination by FAAS. The recovery of sliver was 96.4~101.6%. Results obtained by analysis of a standard sample and some ore samples are satisfactory. In chapter four, the synthetic procedure of PE-dithizone double membranes resin and the optimum conditions for separation and concentrations of gold was studied. Gold can be concentrated on the resin in 0.3 mol/L HCl. The eluted by 5% sulforea-1mol/L HCl and determination by FAAS. The recovery of gold was 91.5~99.7%,RSD<3.1%. Results obtained by analysis of a standard sample and some ore samples are satisfactory. In a word, by numerous systematic and scrupulous experimental works, we have synthesized double membranes resins with high selectivity and large absorptive volume to precious metals of gold, sliver and palladium. Especially, this kind of resin is not only easy to synthesize but also stability and capability of anti-acid-base are very strong. New methods of off-line (FIA) concentration and separation of precious metals have been established successfully. All experimental works make these methods full of theoretical and practical value.